American Express CEO says he recognizes the value of Bitcoin’s technology, among statements which demonstrate an industry still nervous about digital currencies. Speaking at the Dealbook Conference Thursday, Kenneth I. Chenault’s “softer” criticism, as the New York Times describes it, is in stark contrast to comments made by peers MasterCard and Citibank on the same issue. “The protocol of Bitcoin is going to be important,” he said. Such statements hardly sound surprising, but American Express stands out among fiat payment processor giants in its measured response to Bitcoin thus far. Whereas Citibank even went to the extreme of stating that …